The book describes the development of the narrow gauge lines of Western Railway most of which were developed by the rulers of erstwhile Princely States. The largest narrow gauge system was that of the Gaekwar's Baroda State Railway, perhaps the largest narrow gauge system in the world. Other lines described include the Morvi lines, Bilimora - Waghai, Kosamba - Umarpada, Ankleshwar - Rajpipla - Netranj and Piplod - Devgarh Baria. The book explains the development of the lines and describes the rolling stock, particularly, steam locomotives that were used. Since the book was written some sections have been converted to broad gauge, a few closed and the last of the lines are likely to close shortly. The book, therefore is an important historical record for the N.G. System of Western Railway.